The present invention relates to a ring fastener.
Such a ring fastener can be used, for example, to axially locate a stepped shaft in a bore. For this purpose wire rod retaining rings according to the state of the art are known (e.g. DE 26 20 142 C3). With such wire rod retaining rings for shafts or bores, respectively, which, in a locating groove of the shaft or the bore, respectively, in a radially compressed or radially expanded condition, respectively, enable the installation of a corresponding machine part by an axial slide on or insertion operation, respectively, this machine part can be retained axially located in a radially relieved condition and projecting into a catch slot. For this purpose, the ends of these wire rod retaining rings are bent to approx. 10% of the ring length in an inward direction for a shaft or in an outward direction, respectively, for a bore, in such a manner that the ends while holding the wire rod retaining ring essentially concentric to its locating groove, rest against the groove bottom.
From DE 36 35 020 C2 a lock ring made from spring wire is known which comprises inwardly angled ends. Such a lock ring is inserted in the expanded condition into a groove of a stop washer by sliding on so that its angled ends engage an axial recess of the stop washer. The so preassembled construction unit of the stop washer and the lock ring is inserted for installation into a cylindrical housing, with the lock ring being radially contracted to such an extent by means of a clamping tool applied at the angled ends that it completely disappears in the groove of the stop washer during the insertion operation. After the axially locating the preassembled construction unit, the lock ring re-expands radially so that it rests partly in the groove of the stop washer and partly in a circumferential groove of the cylindrical housing and thus axially locates the stop washer in the desired manner.
From DE 12 51 091 B2 a detachable connection of two housing components is disclosed, where the outer circumference of a cylindrical shoulder of the one housing component has an annular groove and the wall of a cylindrical recess of the other housing component accommodating the shoulder has an annular groove which forms a radial extension of the first annular groove. An oval annular body is arranged in both annular grooves, which in the disassembled condition has a circular shape with a diameter between the bottom diameters of the two annular grooves. In the installed condition the annular body is pressed into an oval shape by two screws offset by 180.degree., with the wall of the recess having an enlarged diameter enclosing the shoulder with a generous clearance. This detachable connection can absorb relatively high axial forces. However, its manufacture is relatively expensive, because the screw threads for the two clamping screws must be machined and the clamping screws must be installed in their threads.
Where higher requirements are to be met with respect to the absorption of axial forces and ease of installation, shaft lock rings punched from sheet metal are employed with holes provided in their ends for the application of a clamping tool.
Generally, such shaft lock rings have a cross-section which varies along the circumference of the shaft lock ring. The cross-section in the area of the ends is approximately identical to that in the centre area. The consequence of this is that such lock rings assume an oval shape in the compressed condition. This makes these rings unsuitable under very confined installation conditions.
In cases where such a shaft lock ring has to be installed in or removed from, respectively, the narrow gap between a shouldered shaft and a cylindrical bore, difficulties will be encountered insofar as the conventional assembly tongs tend to slip off the holes of the shaft lock ring. The same applies to shaft lock rings made from wire with bent ring ends. The shaft lock ring often has to be inserted several centimeters deep into the annular gap between the shouldered shaft and the cylindrical bore. This complicates its handling considerably. Finally, the shaft lock ring seated in the cicumferential groove has often engaged the circumferential groove of the bore to such a depth that the holes for tool application or the eyes formed in the angled ends, respectively, are partly hidden by the flanks of the annular groove. The consequence is that the tool can hardly or not at all grasp the shaft lock ring.